LeetCode 093 Restore IP Addresses

class Solution(object):
    # def restoreIpAddresses(self, s):
    #     """
    #     :type s: str
    #     :rtype: List[str]
    #     """
    #     ls = len(s)
    #     if ls == 0 or ls > 12:
    #         return []
    #     if s == '0000':
    #         return ['0.0.0.0']
    #     return self.getremainIP(s, 0, 4)
    #
    # def getremainIP(self, s, pos, count):
    #     if count == 1:
    #         curr = s[pos:]
    #         if self.isNum(curr):
    #             return [curr]
    #     result = []
    #     for i in range(pos, pos + 3):
    #         if i + 1 < len(s):
    #             prefix = s[pos:i + 1]
    #             if self.isNum(prefix):
    #                 res = self.getremainIP(s, i + 1, count - 1)
    #                 result.extend([prefix + '.' + t for t in res])
    #     return result
    #
    # def isNum(self, prefix):
    #     curr = int(prefix)
    #     if curr > 255:
    #         return False
    #     if len(prefix) == 1:
    #         return True
    #     if prefix[0] == '0':
    #         return False
    #     return True

    def restoreIpAddresses(self, s):
        ls = len(s)
        if ls == 0 or ls > 12:
            return []
        res = []
        for i in range(1, 4):
            for j in range(1, 4):
                for k in range(1, 4):
                    m = ls - i - j - k
                    if m > 0 and m <= 3:
                        add1 = s[0:i]
                        add2 = s[i:i + j]
                        add3 = s[i + j:i + j + k]
                        add4 = s[i + j + k:]
                        if self.isValid(add1) and self.isValid(add2) and \
                                        self.isValid(add3) and self.isValid(add4):
                            res.append(add1 + '.' + add2 + '.' + add3 + '.' + add4)
        return res

    def isValid(self, add):
        if len(add) == 1:
            return True
        if add[0] == '0':
            return False
        if int(add) <= 255:
            return True
        return False


if __name__ == '__main__':
    s = Solution()
    # print s.longestValidParentheses(")(((((()())()()))()(()))(")
    print s.restoreIpAddresses('25525511135')